(Source: Flora Malesiana ser. 1, 5: Cyclopaedia of collectors, Supplement I)

(Source: Flora Malesiana ser. 1, 8: Cyclopaedia of collectors, Supplement II)

Born: 1929, Rotterdam, Holland.

career:

Botanist, educated at Leiden University (B.Sc. 1954); Assistant of the Flora Malesiana Foundation, and in Feb. 1955 appointed on the staff of the Bogor Herbarium, Java. In 1959 appointed, on the staff of Flora Malesiana Foundation, at Leiden; subsequently on the staff of the Rijksherbarium; Ph.D. Leiden (1965).

In 1963 he joined a bio-archaeological expedition in West Persia for some months. 

Cyclosorus jacobsii Holtt. has been named after him.

Collecting localities:

1955. W. Java: Udjung Kulon (Aug. 1-7), Tjibodas Mountain Gardens (22-27).-1956. Centr. Sumatra, together with W. Meijer (who made separate collections)¹ Kerintji Distr., G. Kerintji (July 23-30), G. Tudjuh (Aug. 2-7), Danau Bento etc. (8-10); Pajakumbuh, Harau ravine (15), G. Sago (18-19).-1957. E. Java, Besuki Res.²: G. Watangan near Pager (May 10), Nusa Barung (I1-13), G. Raung (S. slope, Gunungsari, 17-19; SE. slope, Baju, 21), G. Merapi (NW. slope, Mailang, 22), G. Baluran (S. foot, 24-25), Blambangan Peninsula (W. part, 28-31, June 2), Djati Ikan Peninsula (N of Blambangan; 2), Kali Pait (N of Gradjagan Bay, 3); W. Java: G. Gedeh, above Tjibodas (Nov. 6); occasionally in Hort. Bog.-1958. Hort. Bog.; Tjibodas (June 15), G. Pangrango (16), G. Gedeh (17), Tjibodas (18). Leaving Bogor (July 20), arriving in Sarawak, NW. Borneo, at Kuching (28); with J.A.R. Anderson to Mt Penrissen (Aug. 1-9; coll. nos 5000-5138); to Sungei Serin limestone hills (10-12, nos 5139-5183); to Belaga on the Rajang River, Segaham Range (Aug. 20-Sept. 7, nos 5184-5465); delta of the Rajang River near Sibu (Sept. 11, nos 5466-5468) ; Seburuan Bau limestone hill near Kuching (14, nos 5469-5484); Bako National Park (16-17, nos 5485-5521); Mt Matang (19-21, nos 5522-5568); Brunei (arriving Sept. 25): with P. Shaw Ashton to E. Brunei, Kuala Belalang (Sept. 29-Oct. 5), riverbeds (nos 5569-?5651); W. Brunei, Andulau Forest Reserve (8, nos 5652-5662), near Telamba bridge on the road Brunei-Kuala Belait (9, nos 5663-5695), Badas Forest Reserve (10, nos 5696-5698), Brunei town (10, no 5699); to N. Borneo (Oct. 12); Ranau (13, no 5700) and with D.I. Nicholson to Mt Kinabalu (14-18, nos 5701-5792);³ leaving Ranau (20), and Singapore (28) for Europe.-1968. Philippines, Luzon. Leaving for Baguio with D.R. Mendoza and R. Espiritu (Jan. 17), camp at Babadak, SW. slope Mt Pulog⁴ (c. 2400 m), and in the top area (from Jan. 28) at c. 2700 m; climbing summit on the 31st; return to Babadak (Feb. 7-10); Mt Tabayoc, camp at 2350m (Feb. 14), visiting the summit (16), 2850m; return to Manila (22); Mar. 7 to lowland forest in the Sierra Madre mountain chain.⁵ E. Luzon, collecting from sea-level up to about 1200 m NE and NW of Dingalan; camp on the road to Baler (Mar. 21-25). S. Sumatra, Prov. of Lampung:⁶ above Giesting on the E. Slope of G. Tanggamus at 1100 m alt. (base camp), collecting from Apr. 25-May 4 (nos 8021-8274), reaching the summit on Apr. 25; primary forest NW of Kota Agung at 350-450 m alt. (May 9-19; nos 8275-8515).

collections:

Herb. Bog. [BO], including 270 nos from Kerintji, 100 nos from Pajakumbuh, and 292 nos (4701-4992) from E. Java.

Borneo collection in Leiden [L], Kew [K]; resp. in Kuching [SAR], Brunei [BRUN], or Sandakan [SAN] (the territory where the collection was made); Geneva [G], Wash. [US], Canberra [CANB], Berlin [B], Stockh. [S], Manila [PNH], Ithaca [BH]. In Herb. Sing. [SING]: Borneo dupl. Annonaceae and Myristicaceae.

Collections made in Hort. Bog., and on G. Gedeh (Nov. 6, 1957; June 1958) are without numbers, mostly for Bailey Hort. Ithaca [BH], N.Y.; dupl. in Dehra Dun [DD].

Mosses from the Philippines (1968), about 600 collections, will be numbered in a B series after study by A. Touw.

literature:

(1) Replace by: M. Jacobs: ‘Contribution to the Botany of Mt Kerintji and adjacent area in West Central Sumatra’ I (Ann. Bog. 3, 1958, p. 45-79, 24 photogr., 1 map).

(2) Replace by: M. Jacobs: ‘Botanical Reconnaissance of Nusa Barung and Blambangan, South East Java’ (Blumea Suppl. 4, 1958, p. 68-86, map, 4 photogr.).

(3) M. Jacobs: ‘Plant Life on Mount Kinabalu’ (Mal. Nat. J. 15, 1961, p. 134-139, map, photogr.).

(4) Cf. Fl. Mal. Bull. no 23, 1969, p. 1686-1687.

M. Jacobs: ‘The Plant World on Luzon’s highest mountains’ (Publ. Rijksherbarium 1972, 32 pp., 16 photogr., 1 drawing, 1 map).

(5) M. Jacobs & D.R. Mendoza: ‘Opportunities and suggestions for botanical exploration work in the Sierra Madre Mountains, Luzon’ (Rijksherbarium Leiden, 1969, folio, stencilled, 14 pp., 1 map).

(6) Cf. Fl. Mal. Bull. no 23, 1969, p. 1685; M. Jacobs: ‘Botanical Exploration in the Lampung Province, Sumatra’ (Reinwardtia 8, 1972, p. 345-349).

biographical data:

Curr. vitae in Thesis Leiden 1965.

photo gallery: